Apparatus and method of transmitting/receiving signals in mobile communication system supporting carries

ABSTRACT

The disclosure relates to methods and systems for converging a 5th-Generation (5G) communication system with technology for Internet of Things (IoT). The disclosure is applicable to intelligent services based on 5G communication and IoT-related technologies. A method for configuring a connection by a terminal is provided, which includes receiving a radio resource control (RRC) message from a base station, determining whether semi-persistent scheduling (SPS) and transmission time interval (TTI) bundling are configured based on the RRC message, determining whether dual connectivity is configured, if the SPS and the TTI bundling are configured, determining whether the TTI bundling is configured for master cell group (MCG) and the SPS is configured for secondary cell group (SCG), if the dual connectivity is configured, and configuring an RRC connection based on the RRC message, if the TTI bundling is configured for the MCG and the SPS is configured for the SCG.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims the benefit under 35 U.S.C. §119(a) of a Koreanpatent application filed on May 16, 2014 in the Korean IntellectualProperty Office and assigned Serial number 10-2014-0059113, the entiredisclosure of which is hereby incorporated by reference.

TECHNICAL FIELD

The present disclosure relates to transmission/reception of signals in amobile communication system. More particularly, the present disclosurerelates to an apparatus and method of transmitting/receiving signals ina mobile communication system supporting a plurality of carriers.

BACKGROUND

Mobile communication systems have been developed to provide acommunication service to users while they are moving. With the rapiddevelopment of technology, mobile communication systems have beendeveloped to provide data communication services at a high speed as wellas voice communication.

In recent years, Long Term Evolution (LTE) that has been developed as anext generation mobile communication system is in process ofstandardization by the 3^(rd) Generation Partnership Project (3GPP). LTEis a technology to implement high speed packet-based communication witha transmission rate of maximum 100 Mbps higher than the datatransmission rate on current technology.

Recently, serious discussions have been made on LTE-Advanced (LTE-A)that enhances the transmission rate by adding various new technologiesto LTE communication systems. One of the technologies to be introducedis Carrier Aggregation (CA) as a typical example. CA refers to atechnology that allows one user equipment (UE) device to use a pluralityof forward carriers and a plurality of reverse carries in datacommunication, compared to the related art where one UE device uses onlyone forward carrier and one reverse carrier.

In LTE-A of the related art, only intra-evolved Node B (eNB) CA has beendefined. This leads to reduce the applicability of CA functions.Particularly, in order to establish a scenario operating a plurality ofpico cells and one micro cell in multiplexing, the LTE-A definitionaccording to the related art cannot aggregate a macro cell and picocells.

To meet the demand for wireless data traffic having increased sincedeployment of 4^(th) Generation (4G) communication systems, efforts havebeen made to develop an improved 5^(th) Generation (5G) or pre-5Gcommunication system. Therefore, the 5G or pre-5G communication systemis also referred to as a ‘Beyond 4G Network’ or a ‘Post LTE System’. The5G communication system is considered to be implemented in higherfrequency (mmWave) bands, e.g., 60 GHz bands, so as to accomplish higherdata rates. To decrease propagation loss of the radio waves and increasethe transmission distance, the beamforming, massive multiple-inputmultiple-output (MIMO), Full Dimensional MIMO (FD-MIMO), array antenna,an analog beam forming, large scale antenna techniques are discussed in5G communication systems. In addition, in 5G communication systems,development for system network improvement is under way based onadvanced small cells, cloud Radio Access Networks (RANs), ultra-densenetworks, device-to-device (D2D) communication, wireless backhaul,moving network, cooperative communication, Coordinated Multi-Points(CoMP), reception-end interference cancellation and the like. In the 5Gsystem, Hybrid Frequency-Shift Keying (FSK) and Feher's QuadratureAmplitude Modulation (FQAM) and sliding window superposition coding(SWSC) as an advanced coding modulation (ACM), and filter bank multicarrier (FBMC), non-orthogonal multiple access (NOMA), and sparse codemultiple access (SCMA) as an advanced access technology have beendeveloped.

The Internet, which is a human centered connectivity network wherehumans generate and consume information, is now evolving to the Internetof Things (IoT) where distributed entities, such as things, exchange andprocess information without human intervention. The Internet ofEverything (IoE), which is a combination of the IoT technology and theBig Data processing technology through connection with a cloud server,has emerged. As technology elements, such as “sensing technology”,“wired/wireless communication and network infrastructure”, “serviceinterface technology”, and “Security technology” have been demanded forIoT implementation, a sensor network, a Machine-to-Machine (M2M)communication, Machine Type Communication (MTC), and so forth have beenrecently researched. Such an IoT environment may provide intelligentInternet technology services that create a new value to human life bycollecting and analyzing data generated among connected things. IoT maybe applied to a variety of fields including smart home, smart building,smart city, smart car or connected cars, smart grid, health care, smartappliances and advanced medical services through convergence andcombination between existing Information Technology (IT) and variousindustrial applications.

In line with this, various attempts have been made to apply 5Gcommunication systems to IoT networks. For example, technologies such asa sensor network, MTC, and M2M communication may be implemented bybeamforming, MIMO, and array antennas. Application of a cloud RAN as theabove-described Big Data processing technology may also be considered tobe as an example of convergence between the 5G technology and the IoTtechnology.

The above information is presented as background information only toassist with an understanding of the present disclosure. No determinationhas been made, and no assertion is made, as to whether any of the abovemight be applicable as prior art with regard to the present disclosure.

SUMMARY

Aspects of the present disclosure are to address at least theabove-mentioned problems and/or disadvantages and to provide at leastthe advantages described below. Accordingly, an aspect of the presentdisclosure is to provide an apparatus and method oftransmitting/receiving signals in a mobile communication systemsupporting a plurality of carriers.

Another aspect of the present disclosure is to provide an apparatus andmethod of transmitting/receiving signals based on inter-evolved Node B(eNB) carrier aggregation (CA) in a mobile communication systemsupporting a plurality of carriers.

In accordance with an aspect of the present disclosure, a method forconfiguring a connection by a terminal is provided. The method includesreceiving a radio resource control (RRC) message from a base station,determining whether semi-persistent scheduling (SPS) and transmissiontime interval (TTI) bundling are configured based on the RRC message,determining whether dual connectivity is configured, if the SPS and theTTI bundling are configured, determining whether the TTI bundling isconfigured for master cell group (MCG) and the SPS is configured forsecondary cell group (SCG), if the dual connectivity is configured, andconfiguring an RRC connection based on the RRC message, if the TTIbundling is configured for the MCG and the SPS is configured for theSCG.

In accordance with another aspect of the present disclosure, a terminalfor configuring a connection is provided. The terminal includes atransceiver configured to at least one of transmit or receive a signal,and a controller configured to receive an RRC message from a basestation, to determine whether SPS and TTI bundling are configured basedon the RRC message, to determine whether dual connectivity isconfigured, if the SPS and the TTI bundling are configured, to determinewhether the TTI bundling is configured for MCG and the SPS is configuredfor SCG, if the dual connectivity is configured, and to configure an RRCconnection based on the RRC message, if the TTI bundling is configuredfor the MCG and the SPS is configured for the SCG.

In accordance with another aspect of the present disclosure, a methodfor configuring a connection by a base station is provided. The methodincludes determining to configure TTI bundling for a terminal on primaryserving cell (PCell), determining whether SPS is configured for theterminal, determining whether the SPS is configured on the PCell orprimary secondary serving cell (PSCell), if the SPS is configured forthe terminal, generating an RRC message indicating configuration of theTTI bundling on the PCell, if the SPS is configured on PSCell, andtransmitting the RRC message to the terminal.

In accordance with another aspect of the present disclosure, a basestation for configuring a connection is provided. The base stationincludes a transceiver configured to at least one of transmit or receivea signal, and a controller configured to determining to configure TTIbundling for a terminal on PCell, to determine whether SPS is configuredfor the terminal, to determine whether the SPS is configured on thePCell or PSCell, if the SPS is configured for the terminal, to generatean RRC message indicating configuration of the TTI bundling on thePCell, if the SPS is configured on PSCell, and transmit the RRC messageto the terminal.

Other aspects, advantages, and salient features of the disclosure willbecome apparent to those skilled in the art from the following detaileddescription, which, taken in conjunction with the annexed drawings,discloses various embodiments of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certainembodiments of the present disclosure will be more apparent from thefollowing description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 is a diagram of a configuration of a Long Term Evolution (LTE)system according to various embodiments of the present disclosure;

FIG. 2 is a diagram of a radio protocol stack in an LTE system accordingto various embodiments of the present disclosure;

FIG. 3 is a diagram that describes an intra-evolved Node B (eNB) carrieraggregation (CA) in an LTE system according to various embodiments ofthe present disclosure;

FIG. 4 is a diagram that describes an inter-eNB CA in an LTE systemaccording to various embodiments of the present disclosure;

FIG. 5 is a diagram that describes connection of a Packet DataConvergence Protocol (PDCP) device in an LTE system according to variousembodiments of the present disclosure;

FIG. 6 is a signal flow chart that describes a process of establishingPrioritized Bit Rate (PBR) by user equipment (UE) that has established amultiple bearer in an LTE system according to a first embodiment of thepresent disclosure;

FIG. 7 is a flow chart that describes a method of automatically alteringPBR by UE in an LTE system according to a first embodiment of thepresent disclosure;

FIG. 8 is a signal flow chart that describes the entire process ofreporting the capability by UE in an LTE system according to a secondembodiment of the present disclosure;

FIG. 9 is a flow chart that describes a method of determining a size ofHybrid Automatic Repeat reQuest (HARQ) buffer by UE in an LTE systemaccording to a second embodiment of the present disclosure;

FIG. 10 is a flow chart that describes a method of determining a size ofHARQ buffer by eNB in an LTE system according to a second embodiment ofthe present disclosure;

FIG. 11 is a flow chart that describes a method of bundling transmissiontime interval (TTI) and establishing semi-persistent scheduling (SPS) byUE in an LTE system according to a third embodiment of the presentdisclosure;

FIG. 12 is a flow chart that describes a method of determining a lengthof HARQ Round Trip Time (RTT) timer by UE in an LTE system according toa fourth embodiment of the present disclosure;

FIG. 13 is a flow chart that describes a process of establishing amultiple bearer by UE in an LTE system according to a fifth embodimentof the present disclosure;

FIG. 14 is a conceptual diagram of Multimedia Broadcast MulticastService (MBMS) according to an embodiment of the present disclosure;

FIG. 15 is a diagram illustrating the mapping relation of downlinkchannel used for Multimedia Broadcast multicast service Single FrequencyNetwork (MBSFN) transmission according to an embodiment of the presentdisclosure;

FIG. 16 is a diagram of a structure of downlink frame used in an LTEsystem according to an embodiment of the present disclosure;

FIG. 17 is a flow chart that describes a method of receiving MBSFN by UEaccording to an embodiment of the present disclosure;

FIG. 18 is a signal flow chart that describes an MBMS counting procedureaccording to an embodiment of the present disclosure;

FIG. 19 is a signal flow chart that describes a method of reporting MBMScounting information to eNB by UE in idle mode according to a sixthembodiment of the present disclosure;

FIG. 20 is a flow chart that describes operations of UE according to asixth embodiment of the present disclosure;

FIG. 21 is a signal flow chart that describes a method of reporting MBMScounting information to eNB by UE in idle mode according to a seventhembodiment of the present disclosure;

FIG. 22 is a flow chart that describes operations of UE according to aseventh embodiment of the present disclosure;

FIG. 23 is a schematic block diagram of UE according to an embodiment ofthe present disclosure; and

FIG. 24 is a schematic block diagram of eNB according to an embodimentof the present disclosure.

Throughout the drawings, it should be noted that like reference numbersare used to depict the same or similar elements, features, andstructures. DETAILED DESCRIPTION

The following description with reference to the accompanying drawings isprovided to assist in a comprehensive understanding of variousembodiments of the present disclosure as defined by the claims and theirequivalents. It includes various specific details to assist in thatunderstanding but these are to be regarded as merely exemplary.Accordingly, those of ordinary skill in the art will recognize thatvarious changes and modifications of the various embodiments describedherein can be made without departing from the scope and spirit of thepresent disclosure. In addition, descriptions of well-known functionsand constructions may be omitted for clarity and conciseness.

The terms and words used in the following description and claims are notlimited to the bibliographical meanings, but, are merely used by theinventor to enable a clear and consistent understanding of the presentdisclosure. Accordingly, it should be apparent to those skilled in theart that the following description of various embodiments of the presentdisclosure is provided for illustration purpose only and not for thepurpose of limiting the present disclosure as defined by the appendedclaims and their equivalents.

It is to be understood that the singular forms “a,” “an,” and “the”include plural referents unless the context clearly dictates otherwise.Thus, for example, reference to “a component surface” includes referenceto one or more of such surfaces.

It will be easily appreciated to those skilled in the art that variousmodifications, additions and substitutions are possible from theembodiment of the present disclosure, and the scope of the presentdisclosure should not be limited to the following embodiments. Thevarious embodiments of the present disclosure are provided such thatthose skilled in the art completely understand the present disclosure.

In the present disclosure, expressions including ordinal numbers, suchas “first,” “second,” etc., and/or the like, may modify variouselements. However, such elements are not limited by the aboveexpressions. For example, the above expressions do not limit thesequence and/or importance of the elements. The above expressions areused merely for the purpose to distinguish an element from the otherelements. For example, a first user device and a second user deviceindicate different user devices although both of them the first userdevice and the second user device are user devices. For example, a firstelement could be termed a second element, and similarly, a secondelement could be also termed a first element without departing from thescope of the present disclosure. The expression “and/or” includes anyand all combinations of the associated listed words. For example, theexpression “A and/or B” may include A, may include B, or may includeboth A and B.

The terms used in the present disclosure are only used to describespecific various embodiments, and are not intended to limit the presentdisclosure. The expressions such as “include” and “may include” whichmay be used in the present disclosure denote the presence of thedisclosed functions, operations, and constituent elements and do notlimit one or more additional functions, operations, and constituentelements. In the present disclosure, the terms such as “ “include”and/or” “have” may be construed to denote a certain characteristic,number, operation, constituent element, component or a combinationthereof, but may not be construed to exclude the existence of or apossibility of addition of one or more other characteristics, numbers,operations, constituent elements, components or combinations thereof.

Unless otherwise defined, all terms including technical and/orscientific terms used herein have the same meaning as commonlyunderstood by one of ordinary skill in the art to which the presentdisclosure pertains. In addition, unless otherwise defined, all termsdefined in generally used dictionaries may not be overly interpreted.

An embodiment of the present disclosure provides an apparatus and methodof transmitting/receiving signals in a mobile communication systemsupporting a plurality of carriers.

In addition, an embodiment of the present disclosure provides anapparatus and method of transmitting/receiving signals based oninter-evolved Node B (eNB) carrier aggregation (CA) in a mobilecommunication system supporting a plurality of carriers.

The apparatus and method according to an embodiment of the presentdisclosure may be applied to various communication systems: for example,Long-Term Evolution (LTE), LTE-Advanced (LTE-A), high speed downlinkpacket access (HSDPA), high speed uplink packet access (HSUPA), highrate packet data (HRPD) of 3^(rd) generation project partnership 2(3GPP2), Wideband Code Division Multiple Access (WCDMA) of 3GPP2, CDMAof 3GPP2, Institute of Electrical and Electronics Engineers (IEEE)802.16m communication system, Evolved Packet System (EPS), MobileInternet Protocol (Mobile IP) system, etc.

The LTE system according to various embodiments of the presentdisclosure is described referring to FIG. 1.

FIG. 1 is a diagram of a configuration of an LTE system according tovarious embodiments of the present disclosure.

Referring to FIG. 1, the LTE system configures the wireless accessnetwork, including eNBs 105, 110, 115, and 120, a Mobility ManagementEntity (MME) 125, and a Serving-Gateway (S-GW) 130. User equipment (UE)135 is connected to an external network via eNBs 105, 110, 115 and 120and S-GW 130. eNBs 105, 110, 115 and 120 correspond to Node B of theUniversal Mobile Telecommunication System (UMTS) according to therelated art. eNBs 105 to 120 are connected to UE 135 via wirelesschannels, performing more complicated functions than Node B of therelated art.

In LTE system, since real-time Voice over IP (VoIP) services and alluser traffics are supported via shared channels, devices are required tocollect information regarding states, such as buffer states of UE,available transmission power states, channel states, etc., and to make aschedule. These tasks are performed via eNBs 105 to 120. One eNB 105,110, 115 or 120 controls a plurality of cells. In order to implement atransmission rate of 100 Mbps, LTE systems employ Orthogonal FrequencyDivision Multiplexing (OFDM) as a wireless access technology, at abandwidth of 20 Mhz. LTE systems also employ Adaptive Modulation &Coding (AMC) to determine modulation scheme and channel coding rate,meeting with the channel state of UE 135.

S-GW 130 is a device that provides data bearers. S-GW 130 forms orremoves data bearers according to the control of MME 125. MME 125manages the mobility of UE 135 and controls a variety of functions. MME125 connects to a plurality of eNBs. In the following description, aradio protocol stack used in an LTE system according to variousembodiments of the present disclosure is explained referring to FIG. 2.

FIG. 2 is a diagram of a radio protocol stack in an LTE system accordingto various embodiments of the present disclosure.

Referring to FIG. 2, in the radio protocol of an LTE system, the radioprotocol between UE and eNB includes various layers, namely Packet DataConvergence Protocol (PDCP) layers 205 and 240, Radio Link Control (RLC)layers 210 and 235, Medium Access Control (MAC) layer 215 and 230,Physical layers (PHY) 220 and 225, respectively.

PDCP layers 205 and 240 perform compression/decompression of IP header.RLC layers 210 and 235 reconfigure PDCP packet data unit (PDU) in propersize and perform Automatic Repeat reQuest (ARQ).

MAC layers 215 and 230 connect to a number of RLC layer devices includedin one UE device. MAC 215 and 230 layers multiplex RLC PDUs to MAC PDUand de-multiplex RLC PDUs from MAC PDU. PHY layers 220 and 225channel-code and modulate data from the upper layers, create OFDMsymbols, and transmit the symbols via a radio channel. In addition, PHYlayers 220 and 225 demodulate and channel-decode OFDM symbolstransmitted via a radio channel, and transfer the symbols to the upperlayers.

In the following description, an intra-eNB CA in an LTE system accordingto various embodiments of the present disclosure is explained referringto FIG. 3.

FIG. 3 is a diagram that describes an intra-eNB CA in an LTE systemaccording to various embodiments of the present disclosure.

Referring to FIG. 3, one eNB broadcasts/receives multi-carriers overfrequency bands. For example, when an eNB 305 broadcasts a forwardcarrier 315 of center frequency f1 and a forward carrier 310 of centerfrequency f3, the related art allows one UE device to transmit/receivedata via one of the carriers 315 and 310.

However, UE 330 capable of performing CA can simultaneouslytransmit/receive data using a number of carriers. eNB 305 can allocatemore carriers to UE 330 capable of performing CA according to theconditions, so that the UE 330 can increase the data transmission rate.As such, the process of aggregating uplink carriers and a forwardcarrier that one eNB broadcasts/receives is referred to as ‘intra-eNBCA.’ However, according to circumstances, in contrast with theembodiment of FIG. 3, a process may be needed for aggregating uplinkcarriers and forward carriers broadcast/received by eNBs that differfrom each other.

In the following description, an inter-eNB CA in an LTE system accordingto various embodiments of the present disclosure is explained referringto FIG. 4.

FIG. 4 is a diagram that describes an inter-eNB CA in an LTE systemaccording to various embodiments of the present disclosure.

Referring to FIG. 4, eNB1 405 broadcasts/receives a carrier of centerfrequency f1 and eNB 2 415 broadcasts/receives a carrier of centerfrequency f2. When UE 430 aggregates the forward carrier of centerfrequency f1 and forward carrier of center frequency f2, this leads to aresult that one UE device aggregates carriers that two or more eNBsbroadcast/receive. This approach is called ‘inter-eNB CA’ in the variousembodiments of the present disclosure. The ‘inter-eNB CA’ is alsoreferred to as ‘Dual Connectivity (DC)’ in the various embodiments ofthe present disclosure. For example, configuration of DC may be used inthe sense of configuration of: inter-eNB CA; one or more cell groups;Secondary Cell Group (SCG); at least one Secondary Cell under thecontrol of an eNB that is not a serving eNB; primary SCell (pSCell); MACentity for a serving eNB (SeNB); two MAC entities to UE; and so on.

In the following description, terms used in the present disclosure areexplained.

In the context of configuration of cell, when one cell is configuredwith one forward carrier broadcast by one eNB and one uplink carrierreceived by the eNB, the term ‘CA’ may be used in the sense that UEsimultaneously transmits/receives data through a number cells. In thatcase, the maximum transmission rate and the number of aggregatedcarriers are correlated positively.

In the following embodiments of the present disclosure, a ‘process thatUE receives data through a forward carrier or transmits data through aforward uplink carrier’ is identical to a ‘process that UEtransmits/receive data using control channel and data channel providedby a cell corresponding to a center frequency and frequency bandcharacterizing the carrier.’ In the various embodiments of the presentdisclosure, ‘CA’ is used in the sense that ‘a plurality of serving cellsare configured,’ in which the terms, Primary serving Cell (PCell) andSecondary serving Cell (SCell), or activated serving cell, etc., will beused. These terms have the same sense as used in LTE mobilecommunication system. In the various embodiments of the presentdisclosure, the term ‘carrier,’ ‘component carrier,’ ‘serving cell,’etc. may be used in the same sense.

In the various embodiments of the present disclosure, a set of servingcells controlled by the same eNB is defined as a ‘Cell Group’ or‘Carrier Group’ abbreviated as ‘CG.’ The CG is divided into ‘Master CellGroup (MCG)’ and ‘Secondary Cell Group (SCG).’

The MCG is a set of serving cells that is controlled by an eNBcontrolling PCell, or Master eNB (MeNB). The SCG is a set of servingcells that is controlled by an eNB controlling only SCells, or Slave eNB(SeNB), not MeNB. eNB informs UE whether a specific serving cell is MCGor SCG in the process of configuring the serving cell.

One UE device may configure one MSG and one or more SCGs. For the sakeof convenience, although the various embodiments of the presentdisclosure are described in such a way that one MSG and one SCG areconfigured in one UE device, it should be understood that the presentdisclosure is not limited to the embodiments. For example, the variousembodiments of the present disclosure may be modified in such a way thatone MSG and two SCGs are configured in one UE device. The terms ‘PCell’and ‘SCell’ are used to differentiate types of serving cells. There aredifferences between PCell and SCell: for example, PCell remains anactivated state and SCell repeats between activated and deactivatedstates according instructions of eNB. PCell serves as a primary servingcell that primarily controls mobility of UE, and SCell serves as asecondary serving cell that performs transmission/reception of data. Inthe various embodiments of the present disclosure, PCell and SCell arereferred to as those defined in LTE specification 36.331 or 36.321, etc.

The various embodiments of the present disclosure consider the presenceof macro cell and pico cell. The macro cell is a cell controlled bymacro eNB and is available in a relatively wide area. The pico cell is acell controlled by SeNB and is available in a much narrower area thanthe macro cell. For example, although it is not any strict standarddifferentiating between PCell and SCell, it may be assumed that a cellrange of a macro cell has a radius of about 500 and a cell range of apico cell has a range of tens of meters. In the various embodiments ofthe present disclosure, the terms a ‘pico cell’ and ‘small cell’ areused in the same sense.

Referring back to FIG. 4, when eNB1 is MeNB and eNB 2 is SeNB, theserving cell 410 of center frequency f1 is a serving cell that belongsto MCG and the serving cell 420 of center frequency f2 is a serving cellthat belongs to SCG.

In the following description, for the sake of convenience, ‘MCG’ and‘SCG’ may be called other terms, e.g., primary set and secondary set,primary carrier group and secondary carrier group, respectively.Although ‘MCG’ and ‘SCG’ are called other terms, it should be understoodthat their functions or operations are identical to those of otherterms, respectively. The reasons of using these terms with differentnames are to differentiate which cell is controlled under an eNBcontrolling PCell of a specific UE device. According to whether or not acell is controlled under an eNB controlling PCell of a specific UEdevice, the cell and the UE device may proceed with differentprocedures, respectively. For example, when a cell is controlled underan eNB controlling PCell of a specific UE device, the cell and the UEdevice may perform operations one mode, respectively; otherwise, thecell and the UE device may perform operations another mode. UE mayconfigure one or more SCGs. For the sake of convenience, although thevarious embodiments of the present disclosure are described in such away that one SCG is configured in UE, it should be understood that thepresent disclosure is not limited to the embodiments. For example, thevarious embodiments of the present disclosure may be modified in such away that a number of SCGs are configured in UE and one of which has aparticular attribute. In intra-eNB CA, UE transmits Channel StateInformation (CSI) and Hybrid ARQ (HARQ) for PCell through PhysicalUplink Control Channel (PUCCH) of the PCell, along with CSI and HARQ forSCell through PUCCH of the PCell. This is to apply CA to UE that isunable to perform simultaneous transmission with Uplink.

In inter-eNB CA, it may be impossible to transmit CSI and HARQ of CSGSCells through PUCCH of PCell. Although HARQ needs to be transmittedwithin HARQ Round Trip Time (RTT), e.g., 8 ms, a transmission delaybetween MeNB and SeNB may be greater than the HARQ RTT. Therefore, oneof the SCells that belonged to SCG is configured with a PUCCHtransmission resource, and HARQ, CSI, etc., for SCG SCells aretransmitted through the PUCCH. The specific SCell is called pSCell. Inthe following description, the inter-eNB CA and DC are used in the samesense.

In the following description, connection of a PDCP device in an LTEsystem according to various embodiments of the present disclosure isexplained referring to FIG. 5.

FIG. 5 is a diagram that describes connection of a PDCP device in an LTEsystem according to various embodiments of the present disclosure.

Referring to FIG. 5, in general, one user service is supported by oneEvolved Packet System (EPS) bearer and one EPS bearer is connected toone radio bearer. The radio bearer includes PDCP and RLC. In inter-eNBCA, RLC and PDCP of one bearer are located in different eNBs, therebyincreasing the efficiency of data transmission/reception. To this end,different approaches are required according to types of user services.

For example, for a large amount of data, a user service may be supportedin such a way that two RLCs are created and data is transmitted/receivedthrough both MeNB and SeNB as shown in diagram 510. For a high level ofQuality of Service (QoS) such as Voice over LTE (VoLTE), a user servicemay be supported in such a way that an RLC is placed in only MeNB anddata is transmitted/received though only the serving cell of MeNB asshown in diagram 505. As shown in diagram 535, a bearer may also beestablished to transmit/receive data through only serving cells ofSeNBs.

In the following description, for the sake of convenience, a bearertransmitting/receiving data through only a serving sell of the MeNB asshown in diagram 505 is called an MCG bearer; a bearer as shown indiagram 510 is called a multiple bearer; and a bearertransmitting/receiving data through only a serving sell of the SeNB asshown in diagram 535 is called an SCG bearer. The PDCP in the MCG bearand SCG bearer is connected to one RLC. The PDCP in the multiple beareris connected to two RLCs. RLCs that transmit/receive data through MCG(or that are connected to MAC related to serving cells of MCG) arecalled MCG RLCs 507 and 515. RLCs that transmit/receive data through SCGare called SCG RLCs 520 and 540. MACs 509 and 525 related totransmission/reception of data through MCG are called MCG-MAC. MACs 530and 545 related to transmission/reception of data through SCG are calledSCG-MAC. MAC and RLC are connected to each other with a logical channel.A logic channel between MCG RLC and MCG-MAC is called MCG logic channel.A logic channel between SCG RLC and SCG-MAC is called SCG logic channel.In the following description, it is assumed, for the sake ofconvenience, that: a macro cell area is an area where a small cellsignal is not received and only macro cell signals are received; and asmall cell area is an area where a macro cell signal and small cellsignals are received. When a UE demanding a large amount of downlinkdata moves from a macro cell area to a small cell area, the UE may beadditionally established with the small cell. Part of the bearers of UEthat have a large amount of downlink data such as a File TransferProtocol (FTP) bearer may be re-configured as a multiple bearer or a SCGbearer in the MCG bearer.

That is, when UE moves from a macro cell area to a small cell area andthen from the small cell area to the macro cell, a bearer of the UE isconfigured from an MCG bearer to a multiple bearer/SCG bearer and thenre-configured from the multiple bearer/SCG bearer to the MCG. In thefollowing description, for the sake of convenience, a bearertransmits/receives: data through MCG when SCG/SeNB has not beenconfigured; however, all or part of data through SCG when SCG/SeNB hasbeen configured, and the bearer is called an ‘offload bearer.’ Thebearer re-configuration may be performed when: SeNB is configured in UE(SeNB addition); SenB is released (SeNB release); or SeNB is changed(SeNB change). When SeNB is configured in UE (SeNB addition), theoffload bearer is re-configured from an MCG bearer to an SCGbearer/multiple bearer. When SenB is released (SeNB release), theoffload bearer is re-configured from an SCG bearer/multiple bearer to anMCG bearer. When SeNB is changed (SeNB change), the offload bearer isre-configured from an SCG bearer/multiple bearer to another SCGbearer/multiple bearer.

Embodiment 1

In the following description, it is assumed that UE is simultaneouslyconnected to and communicates with a plurality of eNBs. It is alsoassumed that one bearer that an eNB has configured with UE can bedivided for the plurality of eNBs. Under these circumstances, a methodof adjusting an amount of data to be transmitted to the respective eNBsis provided as follows.

FIG. 6 is a signal flow chart that describes a process of establishingPBR by UE that has established a multiple bearer in an LTE systemaccording to a first embodiment of the present disclosure. FIG. 6 is aflow chart that describes a logical channel prioritization procedurewhen supporting multiple connections according to the presentdisclosure.

Referring to FIG. 6, it is assumed that UE 601 is simultaneouslyconnected to eNB1 603 and eNB2 605. To this end, it is assumed that UEhas performed a connection procedure with eNB1 supporting multipleconnections, through a procedure such as Random Access, etc. atoperation 611. After the connection procedure, UE receives aconfiguration message for simultaneous communication with eNB2 from eNB1at operation 613. The configuration message may beRRCConnectionReconfiguration that may include operation frequencies,cell identifiers, etc., of eNB1 and eNB2, which are used forsimultaneous communication. The configuration message may also includeconfiguration information about bearers that UE will use for datacommunication.

The UE may be configured with a plurality of bearers that may be used totransmit/receive different types of data, respectively. For example, abearer X may be used for VoLTE data with a high order of priority, and abearer Y may be used for general Internet communication with a low orderof priority.

When UE transmits data using uplink resources allocated by eNB, itdetermines type of data to be transmitted, considering the orders ofpriority of logical channels allocated to respective bearers. When datalasts on a logical channel with a high order of priority, data on alogical channel with a low order of priority may not be processed for arelatively long time. This may cause a problem that it is impossible totransmit/receive at least amount of data to maintain a data session. Inorder to resolve the problem, a concept of Prioritized Bit Rate (PBR) isintroduced. When a PBR is set to a logical channel, UE increases Bj bythe PBR value each Transmission Time Interval (TTI) for the logicalchannel. After that, UE first takes the Bj into consideration todetermine data to be transmitted. For example, although a logicalchannel X with a high order of priority has transmissible data, if theBj of the logical channel X is zero, data on a logical channel that hasa low order of priority and the Bj of which is not zero is firsttransmitted by the Bj. The PBRs are allocated to and managed by logicalchannels, respectively.

In the various embodiments of the present disclosure, it is assumed thatuplink data that belonged to one bearer are separately transmitted toeNB1 and eNB2, and thus the PBR values are set to the respective eNBs 1and 2. In the embodiment of FIG. 6, eNB1 (hereafter, called MCG 603) andeNB2 (hereafter, called SCG 605) are set with PBR values, respectively.In order to transmit traffic that is being transmitted through aspecific bearer to SCG 605, the PBR value of the SCG 605 may be set to arelatively large value or infinity at operation 613.

When receiving the configuration message, UE transmits receptionacknowledgement message at operation 615. The reception acknowledgementmessage may be RRCConnectionReconfigurationComplete. UE establishesrespective bearers based on the configuration message received inoperation 613 at operation 617. In the embodiment of FIG. 6, it isassumed that the PBR value of eNB2 for a bearer a, i.e., the PBR valueof SCG 605, is set to infinity.

When UE is not activated for a frequency of the configured eNB2, itreceives an activation command from the eNB. When UE needs uplinksynchronization of eNB2, it performs an uplink synchronization procedurethrough a process, such as transmission of a preamble for the frequency,etc. at operation 619.

When completing preparation for transmission of uplink data through aphysical channel to SCG, based on the uplink synchronization procedure,UE transmit uplink data according to the PBR value set in operation 617at operations 621, 623, and 625. In the embodiment of FIG. 6, althoughthe bearer a has been established with both eNBs, since the PBR value ofSCG is set to infinity, data is transmitted to only SCG.

Meanwhile, there may be a case that UE does not communicate with SCGsince the UE is moving at operation 631. For example, when UE does notreceive physical signals a preset number of times, it ascertains thatthe radio link is disconnected, which is Radio Link Failure (RLF) atoperation 633.

When RLF occurs since the PBR of SCG is set to infinity and data istransmitted to only SCG, UE is confront with a state where it cannottransmit uplink data through a corresponding bearer until connectionwith the SCG is recovered.

In order to resolve the problem, when RLF occurs in SCG, the PBR valueconfigured by the MCG is set to a preset value or infinity at operation635. The preset value may be set not to exceed the total transmissionrate which is available to the UE according to UE's subscriptioncontract conditions with a telecommunication company. The preset valuemay be a value that has been set before the bearer is re-configured as amultiple bearer. For example, the preset value may be re-configured asthe following table 1. Table 1 shows cases: bearer a is operated as MCGbearer at t1; bearer a is re-configured as a multiple bearer at t2; andRLF of SCG occurs at t3. In the table, the PBR set to M-RLC is identicalto that set to MCG, and the PBR set to S-RLC is identical to that set toSCG.

TABLE 1 PBR set to M-RLC PBR set to S-RLC t0~t1 X kbps Not set to S-RLCt1~t2 infinity Y kbps t3~ UE set PBR of M-RLC from infinity to a presetvalue. The preset value may be a value that has been set before M-RLC (Xkbps) or that has been used before RLF occurs in S-RLC (Y kbps)

Therefore, UE can transmit traffic of a corresponding bearer, which hasbeen transmitted although it is incommunicable in operation 631, throughMCG, thereby maintaining transmission of uplink data at operations 637,639 and 641.

FIG. 7 is a flow chart that describes a method of automatically alteringPBR by UE in an LTE system according to a first embodiment of thepresent disclosure. FIG. 7 is a flow chart that describes operations ofUE with a logical channel prioritization procedure when supportingmultiple connections according to the present disclosure.

Referring to FIG. 7, UE receives information about bearers andinformation about added eNBs that UE will communicate with from eNB atoperation 703. It is assumed that UE is set to communicate with aplurality of eNBs and data that are being transmitted to one bearer maybe transmitted to a plurality of eNBs.

PBR values are applied to respective cell groups (MCG or SCG). UEcalculates an amount of data to be transmitted respective eNBs, by usingthe set values, i.e., PBR values, each time uplink data that UEtransmits to a corresponding bearer is created, and then transmits thedata to the eNBs at operation 705.

An RLF may occur in the cell groups by various causes, e.g., movement ofUE, etc. at operation 707. When UE ascertains that RLF occurred in acell group, it determines whether RLF occurred in MCG or SCG atoperation 709. When UE ascertains that RLF occurred in SCG in operation709, it sets the PBR value of MCG to a new value to continue to transmituplink data through a corresponding bearer at operation 713. That is, UEsets the old PBR value of MCG that has been set by MSG eNB or SCG eNB toa preset value or infinity. The preset value may be set not to exceedthe total transmission rate which is available to the UE according toUE's subscription contract conditions with a telecommunication company.

On the contrary, when UE ascertains that RLF occurred in MCG inoperation 709, it assumes that all connections are disconnectedincluding the disconnection with SCG eNB, and re-configures connectionwith eNB at operation 711.

Therefore, although UE is disconnected in communication with SCG eNB, UEtransmits data to the MCG eNB, thereby maintaining transmission of data.

Embodiment 2

In the following description, according to various embodiments of thepresent disclosure, UE reports a plurality of categories and performHARQ by using one of the categories.

In order to perform transmission/reception of data between UE and eNB,the eNB needs to detect the capability of the UE. For example, eNB needsto have the maximum downlink data rate of UE, the HARQ buffer capabilityof UE, etc., to transmit downlink data to the UE. The capabilityinformation related to transmission/reception of downlink data of UE isreported to eNB in a category form of UE. The following table 2 is ‘UECategory’ defined in Specification 36.306. UE categories may beclassified with respect to the capability to receive downlink data asfollows: Category 1 is 10 Mbps; Category 2 is 50 Mbps; Category 3 is 100Mbps; Category 4 is 150 Mbps; Category 5, 6, and 7 are 300 Mbps; andCategory 8 is 3 Gbps. Since categories of the related art require arelatively high level of processing ability, a new category needs to beintroduced that requires a relatively low level of processing abilityfor UE of low price. The present disclosure employs a new category,e.g., category x. Category x allows for UE supporting a transmissionrate of, for example, about 1 Mbps. The following table 2 describescategory and the related parameters.

TABLE 2 Maximum number of bits Total Maximum received by number numberof UE within of soft layers UE a TTI channel bits supported in Category(1 ms) (Buffer size) downlink Category 1 10296 250368 1 Category 2 510241237248 2 Category 3 102048 1237248 2 Category 4 150752 1827072 2Category 5 299552 3667200 4 Category 6 301504 3667200 2 Category 6′301504 3667200 4 Category 7 301504 3667200 2 Category 7′ 301504 36672004 Category 8 2998560 35982720 8 Category x 1000 12000 1

Categories 1 to 5 were introduced to LTE Specification Release 8.Categories 6 to 8 were introduced to LTE Specification Release 10.Category 11 was introduced to LTE Specification Release 12. Therefore,eNB of Release 8 cannot comprehend Categories 6 to 8, etc. eNB ofRelease 10 cannot comprehend Category x. In the following description,for the sake of convenience, a set of Categories 1 to 5 is calledCategory Group 1; a set of Categories 6 to 8 is called Category Group 2;and Category x is called Category Group 3. Each Category Group mayinclude one or more categories. In part of the present description,Category and Category Group will be used in the same sense.

eNBs of Releases 8 and 9 cannot comprehend Category Groups 2 and 3. eNBsof Releases 10 and 11 cannot comprehend Category Group 3. eNBs ofReleases 12 and the following Release can comprehend all categories.Since UE does not comprehend release of eNB, it may report a number ofcategories according to the states. For example, UE of Category Group 2reports Category Group 1 as well as Category Group 2. UE of CategoryGroup 3 also reports Category Group 1 as well as Category Group 3. Asdescribed below, since category is closely related to the size of a softbuffer, UE and eNB need to employ the same category. Therefore, for UEthat has reported a plurality of categories to eNB, a method is requiredto apply the same category to the UE and eNB. A detailed descriptionabout the items in the table 2 is provided as follows.

Referring to Table 2, as the ‘Maximum number of bits received by UEwithin a TTI (1 ms)’ is multiplied by 1000, it can be converted into themaximum transmission rate per second of a system.

Referring to Table 2, the ‘total number of soft channel bits’ is relatedto the buffer size of UE and affects a rate matching process. When the‘total number of soft channel bits’ is denoted by N_(soft), the softbuffer size for the transport block by N_(IR) bits, and the soft buffersize for the code block by N_(cb) bits, The N_(IR) and N_(cb) areobtained as the following Equation 1.

$\begin{matrix}{{N_{IR} = \lfloor \frac{N_{soft}}{K_{MIMO} \cdot {\min ( {M_{{DL}\; \_ \; {HARQ}},M_{limit}} )}} \rfloor},{N_{cb} = {\min ( {\lfloor \frac{N_{IR}}{C} \rfloor,K_{w}} )}}} & {{Equation}\mspace{14mu} 1}\end{matrix}$

Where K_(MIMO) is equal to 1 or 2 based on transmission modes and min(M_(DL) _(—) _(HARQ) M_(limit)) is a constant, 8. C is the number ofcode blocks. K_(W) is the circular buffer of length, K_(w)=3K_(II).K_(w) is 6144 bits as the inter-leaver sub-block size. That is, asexpressed in Equation 1, N_(soft) affects N_(IR). When N_(IR)/C is lessthan K_(w), or when data is transmitted/received at a high rate, N_(IR)affects N_(cb). Since puncturing/repetition pattern is affectedaccording to the N_(cb), if N_(soft) between UE and eNB is correctlycomprehended, it will be easily appreciated that malfunctions may occur.The other details related to rate matching, etc., follow Specification36.212.

FIG. 8 is a signal flow chart that describes the entire process ofreporting the capability by UE in an LTE system according to a secondembodiment of the present disclosure.

Referring to FIG. 8, in a mobile communication system including UE 805,eNB 810 and MME 815, UE is turned on at operation 820. UE searches cellsfor an accessible cell. When UE searched an accessible cell, it performsa Radio Resource Control (RRC) connection establishment procedure (referto Specification 36.331) to establish an RRC connection with eNB throughthe cell at operation 825. UE transmits control messages to MME throughthe established RRC connection at operation 830. The control messagesmay be a message for requesting a start of services, SERVICE REQUEST, ora message for requesting an initial registration, ATTACH REQUEST.

MME determines whether to accept the UE's request through a procedure.When MME accepts the UE's request and determines to provide a mobilecommunication service to the UE, it transmits a control messageincluding information about the UE to the eNB at operation 835. Thecontrol message may include information that the eNB needs to use totransmit/receive data to/from the UE, e.g., security key, serviceprofile information about the UE, etc. When the MME has includedcapability information about the UE, it may also include the capabilityinformation in the control message.

On the contrary, when the MME has not included capability informationabout the UE, the eNB transmits an RRC control message to the UE inorder to obtain the capability information about the UE at operation840. The RRC control message is UE CAPABILITY ENQUIRY and may include afield containing an instruction requesting the capability of RadioAccess Technology (RAT). LTE eNB may configure the field to request thecapability about E-UTRA. When the UE receives the RRC control message,it checks the capability of a requested RAT.

When the UE ascertains that the capability of E-UTRA is requestedthrough the RRC control message, it creates a message containing thecapability related to E-UTRA, UE CAPABILITY INFORMATION, and transmitsthe message to the eNB at operation 845. The UE CAPABILITY INFORMATIONmay include information about at least one category. As described below,category information contained in the UE CAPABILITY INFORMATION may varyaccording to categories of capability that UE reporting the UECAPABILITY INFORMATION belonged to.

When the capability of UE corresponds to one of Categories 1 to 5, theUE reports only Category Group 1 that its capability belonged to.

When the capability of UE corresponds to one of Categories 6 to 8, theUE reports Category Group 2 that its capability belonged to and CategoryGroup 1 similar to Category Group 2. For example, UE of Category 6 or 7reports Category 4 as Category Group 1. UE of Category 8 reportsCategory 5 as Category Group 1.

When the capability of UE corresponds to Category x, the UE reportsCategory Group 3 that its capability belonged to and Category Group 1similar to Category Group 3. For example, UE of Category x reportsCategory x as Category Group 3. UE of Category x reports Category 1 asCategory Group 1.

When eNB receives the capability information about the UE, it determinesthe configuration for the UE based on the capability information, andalso Category to be applied to the UE at operation 850.

The eNB may configure an antenna, a transmission mode (TM), CA, etc.,and determines a Category to be applied, considering the configuration,according to a rule. The rule will be described in detail referring toFIG. 8. The eNB transmits a control message (e.g., RRC connectionre-configuration message) containing the configuration information tothe UE at operation 855. The control message includes information abouta category that the UE has applied to the UE. The UE may configure anantenna, a TM, CA, etc., by applying the configuration information inthe control message. The UE determines a category to be applied, basedon the configuration information in the control message, andre-configures the downlink HARQ soft buffer according to the determinedcategory at operation 860.

The eNB configures a downlink HARQ buffer by applying N_(soft) of thedetermined category, and transmits downlink data to the UE by using theHARQ buffer at operation 865. For example, the eNB determines N_(IR) byapplying N_(soft) of the determined category, and determines the HARQsoft buffer size according to the N_(IR). If N_(soft) and N_(IR) arealtered, the soft buffer size is also altered to comply with thealterations. If the re-configured soft buffer size is reduced to be lessthan the previous soft buffer size, the UE removes data from the softbuffer, which is more than the re-configured soft buffer size, leavingonly data in the soft buffer, which is less than the re-configured softbuffer size. This process is called a ‘data management in soft bufferre-configuration.’

The UE receives downlink data from the eNB by using the re-configuredsoft buffer at operation 865.

After that, the eNB may alter the configuration of the UE at any time.This leads to the alteration of category to be applied at operation 870.For example, when the UE is requested for a handover to a new eNB, ifthe new eNB cannot comprehend part of the category of the UE since therelease version of the new eNB is lower than that of the previous eNB, anew category needs to be applied. For example, when a target eNBdetermines configuration information to be applied to UE after ahandover for the UE and transmits it to a source eNB, the source eNBtransmits an RRC connection re-configuration message containing theconfiguration information to the UE at operation 875. The RRC connectionre-configuration message includes a control message for handover. The UEestablishes downlink synchronization with the target cell indicated bythe control message. The UE determines a category to be applied in thetarget cell, by using the information contained in the RRC connectionre-configuration message. After that, the UE re-configures the downlinksoft buffer according to the determined category at operation 880. TheUE receives downlink data from the target cell by using there-configured downlink soft buffer at operation 885. In particular, whenthe UE has established downlink synchronization with the target cell, itperforms Random Access procedure in the target cell. After completingthe Random Access procedure, the UE starts using the re-configureddownlink soft buffer.

FIG. 9 is a flow chart that describes a method of determining a size ofHARQ buffer by UE in an LTE system according to a second embodiment ofthe present disclosure.

UE determines the category before it starts performing the procedureshown in FIG. 9. Category of UE may be determined during themanufacturing process and stored in the non-volatile memory, etc. Asdescribed above, UE may have at least one category. UE that belongs toCategory Group 3 also has Category Group 1 that old eNBs can recognizein order to prepare for a case where the UE is connected to the oldeNBs. When the UE is turned on, it selects an appropriate cell that itwill camp on, through a cell search process, and then performs a networkaccess procedure through the cell at operation 905. The eNB broadcasts acondition as to whether it supports Category Group 3 in a correspondingcell, through the system information. The UE first connects to a cellwhere Category Group 3 is supported.

The UE reports the capability information along with the UE's categoryat operation 910. UE of Category Group 3 reports Category Group 1 andCategory Group 3. The UE reports category 1, which is most similar toCategory Group 3, as Category Group 1. The UE reports category x asCategory Group 3.

The UE checks whether the current serving cell supports Category Group 3in order to compute N_(soft) by applying one of the two reportedcategories at operation 915. For example, the UE checks whether SystemInformation Block (SIB) of the system information about a serving cell(e.g., SIB 1 or SIB 2) contains control information (e.g., informationas to whether the cell supports Category Group 3).

When the UE ascertains that the current serving cell does not supportCategory Group 3 in operation 915, it determines N_(soft) by applyingCategory Group 1 at operation 920. For example, when the UE has reportedCategory x as Category Group 3 and also Category 1 as Category Group 1,it applies Category 1.

When the UE ascertains that the current serving cell supports CategoryGroup 3 in operation 915, it determines N_(soft) by applying CategoryGroup 3 at operation 925. For example, when the UE has reported Categoryx as Category Group 3 and also Category 1 as Category Group 1, itapplies Category x.

FIG. 10 is a flow chart that describes a method of determining a size ofHARQ buffer by eNB in an LTE system according to a second embodiment ofthe present disclosure.

Referring to FIG. 10, the eNB obtains category information about UE withwhich the eNB has established an RRC connection at operation 1005.

The eNB checks the category information type and determines thefollowing process at operation 1010. When the category informationincludes Category 1 and Category 2, the eNB proceeds with operation1015. When the category information includes only Category 1, the eNBproceeds with operation 1025. When the category information includesCategory 1 and Category 3, the eNB proceeds with operation 1030.

The eNB checks whether the application condition for Category Group 2 issatisfied in operation 1015. When the eNB ascertains that theapplication condition for Category Group 2 is satisfied in operation1015, it proceeds with operation 1020. When the eNB ascertains that theapplication condition for Category Group 2 is not satisfied in operation1015, it proceeds with operation 1025. The application condition forCategory Group 2 is one of the following cases:

Condition 1 to select Category Group 2: No serving cell configured in TM10, and at least one serving cell configured in TM 9

Condition 2 to select Category Group 2: UE is configured for: servingcells of up to maximum two; and at least one serving cell configured inTM 9

The conditions to select a category are classified according totransmission modes defend in UE.

TM 9 and TM 10 are forward transmission modes defined in Specification36.213. TM 9 is a mode where single-user multiple-input multiple-output(SU-MIMO) with links of up to maximum 8 is supported. TM 10 is a modewhere Coordinated Multi-Point transmission (CoMP) is supported. As atransmission mode to which a high data transmission rate is likely to beapplied is previously correlated with a category of a high datatransmission rate, the eNB can determine a corresponding category to beapplied.

The eNB determines N_(soft) by applying Category Group 2 when performingdownlink HARQ to UE at operation 1020.

The eNB determines N_(soft) by applying Category Group 1 when performingdownlink HARQ to UE at operation 1025.

The eNB checks whether a serving cell of UE supports Category Group 3 atoperation 1030. When the eNB ascertains that a serving cell of UE doesnot support Category Group 3 in operation 1030, it proceeds withoperation 1025.

When the eNB ascertains that a serving cell of UE supports CategoryGroup 3 in operation 1030, it determines N_(soft) by applying CategoryGroup 3 when performing downlink HARQ to UE at operation 1035.

256 Quadrature Amplitude Modulation (QAM) is supported since 3GPPRelease 12. Since 256 QAM requires the change in hardware between UE andeNB, it is supported by not all devices. Another embodiment of thepresent disclosure provides a method of checking whether UE supports 256QAM by using UE category and UE release information (refer toaccessStratumRelease, Specification 36.331).

UE reports UE category and UE release information to eNB through thecapability report message. Release information shows a release of LTEstandards by which UE has been implemented.

The UE category and UE release information have a feature that UE mustreport them to eNB regardless of whether it supports 256 QAM. Accordingto a tacit standard between UE and eNB, UE devices that belong tocategories since Release 12 support 256 QAM. UE does not need to provideadditional information in order to report a condition as to whether itsupports 256 QAM. eNB checks Release and Category of UE and determineswhether UE supports 256 QAM.

In the following description, Category related to a condition as towhether to support 256 QAM is called 256 QAM Category. 256 QAM Categorymay be, for example, Category 4, Category 5, Category 6, Category 7,Category 8, etc. That is, from among the UE devices that have reportedthat they support at least one of the categories, UE devices of aversion of Release (e.g., Release 12) and beyond report a condition asto whether they support 256 QAM.

As described above, UE always reports categories of Category Group 1;however may or may not report categories of Category Group 2 or CategoryGroup 3. Therefore, UE of Release 12 and beyond is designed to reporttwo or more categories. In that case, any one of the categories belongsto 256 QAM Category, the UE is determined as UE that supports 256 QAM.

According to an embodiment of the present disclosure, UE sets: firstinformation (UE category information) indicating the buffer size andtransmission rate to a predetermined first value; and second information(UE release information) indicating a version of release by which the UEhas been implemented to a predetermined second value that is greaterthan the first value, in order to report a condition as to whether itsupports 256 QAM. The UE may transmit plural first information and oneof them may set to a predetermined value.

When eNB receives the capability information about UE and detects thatthe first information reported by the UE is a first value and a secondvalue of the second information is greater than the first value, itascertains that the UE supports 256 QAM. When the eNB ascertains that adownlink channel status of the UE satisfies a preset condition (orbetter than a preset standard), it transmits 256 QAM modulated downlinkdata to the UE.

Embodiment 3

Embodiment 3 is related to operations between eNB and UE configuring SPSand TTI bundling.

TTI bundling is processes for transmitting the same data through foursuccessive sub-frames in order to resolve the lack of reversetransmission output power that occurs during the cell change.Semi-Persistent Scheduling (SPS) is to allocate fixed resources in orderto effectively support services that continuously create packets of afixed size at a fixed period, such as a VoIP service. SPS reduces theamount of PDCCH used and increases the number of VoIP service userssupportable once.

When UE runs on in a macro cell, TTI bundling and SPS may be applied atthe same time, but instead the efficiency may decrease. Applying TTIbundling means a state where UE is located in alteration of a macrocell. In that case, the channel status of the UE is unstable. Therefore,it is more efficient to allocate dynamical transmission resources byreflecting the channel status of the UE than fixed resources by SPS.

When UE operates in DC, the UE transmits/receives data to/from a macrocell and a small cell, simultaneously. If the UE is geographicallylocated in alteration of a macro cell, it needs to apply TTI bundling inorder to perform transmission/reception of data in the macro cell. Onthe contrary, the UE may experience a channel environment in a smallcell that is quite different from that of the macro cell, and may stilluse SPS.

Considering the conditions described above, the various embodiments ofthe present disclosure allow for simultaneous configuration of TTIbundling and SPS with respect to a particular condition (e.g., DC hasbeen configured in UE, TTI bundling in PCell, and SPS in PSCell);however, do not allow for simultaneous configuration of TTI bundling andSPS with respect to the other cases.

The eNB determines whether to configure SPS considering a TTI bundlingconfiguration condition of UE or whether to configure TTI bundlingconsidering an SPS configuration condition. When UE receive a controlmessage instructing a simultaneous configuration of TTI bundling andSPS, it determines whether the control message is proper and thenfollows the instruction of the control message.

FIG. 11 is a flow chart that describes operations of UE according to anembodiment of the present disclosure.

Referring to FIG. 11, UE receives a control message instructing RRCconnection re-configuration, RRC CONNECTION RECONFIGURATION, from eNB(refer to Specification 36.331) at operation 1105.

When UE re-configures RRC connection according to the control message,it determines whether a simultaneous configuration of TTI bundling andSPC is configured at operation 1110. When UE ascertains that asimultaneous configuration of TTI bundling and SPC is configured inoperation 1110, it proceeds with operation 1120. When UE ascertains thata simultaneous configuration of TTI bundling and SPC is not configuredin operation 1110, it proceeds with operation 1115. For example, whenTTI bundling has been configured before the UE receives the controlmessage and the received control message instructs a configuration ofSPS, the UE proceeds with operation 1120. Similarly, when SPS has beenconfigured before the UE receives the control message and the receivedcontrol message instructs to apply TTI bundling, the UE proceeds withoperation 1120. When the UE meets any case other than the two casesabove, it proceeds with operation 1115. Configuring SPS is used in thesame sense of providing an SPS transmission resource period,semiPersistSchedIntervalDL, semiPersistSchedIntervalUL (refer toSpecification 36.331) and information about HARQ process that SPStransmission resources will use (numberOfConfSPS-Processes (refer toSpecification 36.331) to the UE through the RRC control message.Configuring TTI bundling is used in the same sense of containing aninformation element (IE) of ttiBundling set to TRUE in an RRC controlmessage.

The UE re-configures an RRC connection according to the instruction ofthe received RRC control message at operation 1115. For example, whenthe control message instructs to configure TTI bundling, the UE appliesTTI bundling in a serving cell (e.g., PCell).

In order to determine whether UE can configure a simultaneousconfiguration of TTI bundling and SPC, the UE checks whether theconfiguration of the UE is the following configuration, Configuration 1,according to the instruction of the control message at operation 1120.When the UE ascertains that the configuration of the UE is the followingconfiguration, Configuration 1, in operation 1120, it proceeds withoperation 1130. On the contrary, when the UE ascertains that theconfiguration of the UE is not the following configuration,Configuration 1, in operation 1120, it proceeds with operation 1125. Forexample, when the control message directly indicates Configuration 1, orthe UE has been set with Configuration 1 before receiving the controlmessage, the UE proceeds with operation 1130.

[Configuration 1]

At least one SCG is configured (i.e., DC is configured), and only oneuplink is set in MCG (i.e., a serving cell where only PCell is set withuplink and the other cells, SCells, are set with downlink).

The UE detects that the received control message or the currentconfiguration has failed and performs the following process at operation1135. Examples of the following process are below.

[Following Process 1]

Ignoring the received RRC control message and performing RRC connectionreestablishment procedure (refer to Specification 36.331)

[Following Process 2]

Ignoring the received RRC control message and maintaining the currentconfiguration

[Following Process 3]

Configuring only one function of TTI bundling and SPS and reservingconfiguration of the other functions. In general, since TTI bundling ismuch more important than SPS when marinating the connection of UE, onlyTTI bundling is applied. SPS is not applied.

The UE determines whether TTI bundling is configured for only MCG (orPCell) and SPS is configured for only SCG (or PSCell) in operation 1130.When the UE ascertains that TTI bundling is configured for only MCG andSPS is configured for only SCG in operation 1130, it proceeds withoperation 1135. On the contrary, when the UE ascertains that thedetermination does not satisfy the condition, for example, SPS isconfigured for MCG, it proceeds with operation 1125. Configuring TTIbundling for only MCG means that MAC configuration information for MCG(MAC-mainConfig) includes ttiBundling information, indicated to UE, andMAC configuration information for SCG (or control informationconfiguring SCG or control information configuring PSCell) does notinclude ttiBundling information.

Configuring SPS for only SCG (or PSCell) means that configurationinformation related to SPS (SPS-config) is not included in MACconfiguration information about MCG but is included in MAC configurationinformation about SCG (or control information configuring SCG or controlinformation configuring PSCell).

The eNB may determine to configure transmission time interval (TTI)bundling for an UE on PCell, may determine whether SPS is configured forthe UE, may determine whether the SPS is configured on the PCell orPSCell if the SPS is configured for the UE, may generate a radioresource control (RRC) message indicating configuration of the TTIbundling on the PCell if the SPS is configured on PSCell, and maytransmit the RRC message to the UE. The eNB may determine to configureTTI bundling for the terminal on PCell based on channel status of theterminal and based on available transmission power of the terminal. TheTTI bundling is not configured on the PCell if the SPS is configured onthe PCell.

Embodiment 4

Another embodiment of the present disclosure provides a method ofperforming downlink HARQ by UE operating in Discontinuous Reception(DRX) mode. In particular, the embodiment of the present disclosureprovides a method of determining a length (time interval) of HARQ RTTtimer that UE drives to receive HARQ re-transmission.

When UE operating in DRX mode receives downlink data, it is triggereduntil Active Time in order to receive re-transmission for the downlinkdata after a time interval set by the HARQ RTT time has elapsed. TheHARQ RTT timer is set to stop after four subframes from a time pointthat the UE transmitted the HARQ feedback in response to the downlinkdata; has a fixed value of eight subframes in an FDD serving cell; andis defined as (k+4) subframes in a TDD serving cell, where k is a valuedefined according to the TDD configuration and follows the definition inSpecification 36.213.

In the present disclosure, UE determines a time interval of the HARQ RTTtimer, considering the type of serving cell that has received downlinkdata.

A method of determining operations of UE in subframe n is describedreferring to FIG. 12.

FIG. 12 is a flow chart that describes a method of determining a lengthof HARQ RTT timer by UE in an LTE system according to a fourthembodiment of the present disclosure.

Referring to FIG. 12, the UE checks whether subframe n satisfiesconditions as follows at operation 1205. When the UE ascertains thatsubframe n satisfies the following conditions in operation 1205, itproceeds with operation 1215. When the UE ascertains that subframe ndoes not satisfy the following conditions in operation 1205, it proceedswith operation 1210.

Conditions

A corresponding subframe is: Active Time (which is a period of time thatUE operating in DRX is monitoring PDCCH, specified in Specification36.321); is PDCCH subframes (which transmit/receive PDCCH, specified inSpecification 36.321); but is not part of configured measurement gap(specified in Specification 36.321).

When the UE ascertains that all the conditions are satisfied, itproceeds with operation 1215. When the UE ascertains that any one of theconditions is not satisfied, it proceeds with operation 1210 and waitsuntil the operation of the next subframe is determined.

The UE monitors PDCCH of subframe n at operation 1215. That is, the UEmonitors whether scheduling information addressed to C-RNTI of the UE isreceived thorough the PDCCH.

The UE checks whether downlink transmission is instructed through PDCCHof subframe n or downlink transmission resource assignment is configuredto subframe n at operation 1220. When the UE ascertains that downlinktransmission is instructed through PDCCH of subframe n or downlinktransmission resource assignment is configured to subframe n inoperation 1220, it proceeds with operation 1220. When the UE ascertainsthat downlink transmission is not instructed through PDCCH of subframe nor downlink transmission resource assignment is not configured tosubframe n in operation 1220, it proceeds with operation 1210. Theconfiguration of downlink transmission resources may be, e.g., a casewhere downlink SPS is configured in a corresponding subframe.

The UE starts HARQ RTT timer at operation 1225 and receives downlinkdata according to the PDCCH on a cell belonging to a cell group. Whendecoding received downlink data is failed, the UE remains Active Timestate or triggers Active Time in order to receive re-transmission afterthe HARQ RTT time has expired.

In order to determine a length (time interval) of HARQ RTT timer, itproceeds with operation 1230. The operations 1230 to 1255 fordetermining a length of HARQ RTT timer may be performed before operation1225.

The UE checks whether a serving cell receiving the downlink data is MCGor SCG at operation 1230. The HARQ RTT timer is set to predeterminednumber of subframes based on the cell group where the downlinkassignment is received and based on a duplex mode of PCell or PSCell.When the UE ascertains that a serving cell receiving the downlink datais MCG in operation 1230, it proceeds with operation 1235. On thecontrary, when the UE ascertains that a serving cell receiving thedownlink data is SCG in operation 1230, it proceeds with operation 1250.

The UE checks whether PCell is operated in FDD or TDD at operation 1235.When the UE ascertains that PCell is operated in FDD in operation 1235,it proceeds with operation 1245. On the contrary, when the UE ascertainsthat PCell is operated in TDD in operation 1235, it proceeds withoperation 1240.

The UE determines K according to UL/DL configuration of PCell atoperation 1240. The relationship between K and TDD UL/DL configurationfollows Table 10.1.3.1-1 of Specification 36.213. The value of HARQ RTTtimer is set to K+4.

The UE sets the length of HARQ RTT timer to eight subframes at operation1245.

The UE checks whether PSCell is operated in FDD or TDD at operation1250. When the UE ascertains that PSCell is operated in FDD in operation1250, it proceeds with operation 1245. On the contrary, when the UEascertains that PSCell is operated in TDD in operation 1250, it proceedswith operation 1255.

The UE determines K according to UL/DL configuration of PSCell atoperation 1255. The relationship between K and TDD UL/DL configurationfollows Table 10.1.3.1-1 of Specification 36.213. The value of HARQ RTTtimer is set to K+4.

When the UE ascertains that PCell is operated in FDD, it sets the HARQRTT timer for all MCG serving cells to eight. When the UE ascertainsthat PCell is operated in TDD, it sets the HARQ RTT timer for all MCGserving cells is set to k+4. k is determined according to TDD UL/DLconfiguration of PCell.

When the UE ascertains that PSCell is operated in FDD, it sets the HARQRTT timer for all SCG serving cells to eight. When the UE ascertainsthat PSCell is operated in TDD, it sets the HARQ RTT timer for all SCGserving cells is set to k+4. k is determined according to TDD UL/DLconfiguration of PSCell.

Embodiment 5

RLC indicates the last byte of PDCP packet included in RLC packet byusing a field of Length Indicator (LI). The length of LI needs to bedefined so that it can express the maximum size of the PDCP packet. OnePDCP packet corresponds to one IP packet. The IP packet size isvariable. The maximum size of IP packet may be ten thousands of bytes or1500 bytes according to the characteristics of IP stream or serversproviding IP stream.

In the present disclosure, UE sets lengths of LI to be different by IPstreams, according to instructions of eNB. In general, since one IPstream is supported by one EPS bearer and one EPS bearer is supported byone Radio Bearer, the LI lengths according to the present are setaccording to EPS bearers or Radio Bearers.

When a Radio Bearer is mapped to MCG, the length of LI for the RadioBearer is determined by MeNB.

When a Radio Bearer is re-configured from MCG bearer to SCG bearer, thelength of LI for the bearer is determined by SeNB. Therefore, the lengthof LI for one Radio Bearer/EPS bearer varies according to whether thebearer is configured in MCG or SCG.

That is, the length of LI when the RLC of a Radio Bearer is configuredin MeNB differs from that when the RLC of a Radio Bearer is configuredin SeNB.

For a multiple bearer, one PDCP is connected to two RLCs and the RLCsare set in MeNB and SeNB, respectively. If LIs of different lengths areset to the two RLCs, the PDCP needs to transmit/receive PDCP packets tothe two RLCs, which differ from each in the maximum size, respectively.This causes UE and eNB to increase in complexity. Therefore, the presentdisclosure sets the lengths of LIs for data transmitted/received throughMeNB and SeNB to be either identical or different.

When the Radio Bearer is a multiple bearer, the LI length of RLC packettransmitted/received through MeNB need to be identical to that of datatransmitted/received through SeNB. On the contrary, when the RadioBearer is not a multiple bearer, the LI length of RLC packettransmitted/received through MeNB may differ from that of datatransmitted/received through SeNB.

FIG. 13 is a flow chart that describes operations of UE according to afifth embodiment of the present disclosure.

Referring to FIG. 13, UE receives a control message instructing RRCconnection re-configuration, RRC CONNECTION RECONFIGURATION, from eNB(refer to Specification 36.331) at operation 1305.

When UE re-configures RRC connection according to the control message,it determines whether a multiple bearer is configured at operation 1310.When the UE ascertains that a multiple bearer is configured in operation1310, it proceeds with operation 1320. On the contrary, when the UEascertains that a multiple bearer is not configured in operation 1310,it proceeds with operation 1315. Configuring a multiple bearer meansthat one Radio Bearer is configured with one PDCP and two RLCs, wherethe respective RLCs can perform transmission/reception, one RLC is setto transmit/receive data through MCG, and the other is set totransmit/receive data through SCG.

The UE re-configures RRC connection according to the instruction of thereceived RRC control message at operation 1315.

The UE checks whether the LI lengths of the RLCs of the multiple bearerare set to be identical to each other at operation 1320. That is, the UEchecks whether the lengths of LIs of the RLC transmitting/receiving datathrough SCG (S-RLC) and the RLC transmitting/receiving data through MCG(M-RLC) are set to be identical to each other. When the UE ascertainsthat the LI lengths of the RLCs of the multiple bearer are set to beidentical to each other in operation 1320, it proceeds with operation1330. On the contrary, when the UE ascertains that the LI lengths of theRLCs of the multiple bearer are not set to be identical to each other inoperation 1320, it proceeds with operation 1325.

The UE detects that the received control message has failed and performsthe following process at operation 1325. Examples of the followingprocess are below.

[Following Process 1]

Ignoring the received RRC control message and performing RRC connectionreestablishment procedure (refer to Specification 36.331)

[Following Process 2]

Ignoring the received RRC control message and maintaining the currentconfiguration

In order to prevent that the lengths of LI of M-RLC and S-RLC areunintentionally set to be different from each other, it may be designedin such a way that the length of LI is set for only one of the two RLCand the LI length of the other RLC is set to be identical to that ofother RLCs in the same bearer. That is, when the LI length of M-RLC hasbeen set, information about the LI length of S-RLC is not signaled.Although information about the LI length of S-RLC is signaled, the UEignores the information and sets the LI length of S-RLC and the LIlength of M-RLC to be identical to each other.

MeNB and SeNB exchange control signals with each other in order tore-configure a Radio Bearer from MCG bearer to a multiple bearer.

When NeMB transmits a control message for requesting multiple bearerconfiguration (e.g., a request message of SCG configuration change) toSeNB, the SeNB transmits a control message (e.g., an acceptance messageof SCG configuration change request) including real configurationinformation about a multiple bearer to the MeNB. The acceptance messageof SCG configuration change request includes S-RLC configurationinformation about S-RLC, etc. MeNB transmits the S-RLC configurationinformation, etc. to the UE, without correcting it.

The eNB may perform the following processes so that the LI lengths ofM-RLC and S-RLC of a multiple bearer are identical to each other.

When MeNB requests configuration of a multiple bearer from SeNB, theMeNB transmits, to the SeNB, a request message of SCG configurationchange, including RLC configuration information about an M-RLC of themultiple bearer requested for configuration. The RLC configurationinformation includes information about an LI length of the M-RLC. TheSeNB selects an LI length of the S-RLC of the multiple bearer to beidentical to the LI length of the M-RLC.

As another example, when SeNB selects the LI length of the S-RLC of amultiple bearer as an arbitrary value and transmits an acceptancemessage of SCG configuration change request to the MeNB, the MeNB checksthe LI length of the S-RLC. When the MeNB ascertains that the LI lengthof the S-RLC selected by the SeNB is identical to that of the M-RLC, theMeNB performs the following processes. On the contrary, when the MeNBascertains that the LI length of the S-RLC selected by the SeNB differsfrom that of the M-RLC, the MeNB re-configures the M-RLC so that the LIlength of the M-RLC is set to be identical to that of the S-RLC.

Embodiment 6

The embodiment of the present disclosure relates to an apparatus andmethod of allowing eNB to effectively collect information about MBMSservices or MBMS services of interest that UE in idle mode arereceiving. In current LTE standard technology, eNB can collect theinformation described above, from UE only operating in connection mode.To this end, eNB uses an MBSM counting procedure. The present disclosureprovides a method of collecting the information described above from UEoperating in idle mode. In particular, according to the presentdisclosure, UE in idle mode ignores current Access Class Barring (ACB)or uses a Random Access Technique in order to transmit the informationdescribed above to eNB.

In the following description, MBMS related technology in LTE standard isdescribed before explain the present disclosure.

FIG. 14 is a conceptual diagram of MBMS according to an embodiment ofthe present disclosure.

An MBMS service area 1400 is a network area where a plurality of eNBsperforms transmission of Multimedia Broadcast multicast service SingleFrequency Network (MBSFN).

An MBSFN Area 1405 is a network area where a number of cells areintegrated to perform transmission of MBSFN and the cells are allsynchronized for MBSFN transmission.

All cells except for MBSFN Area Reserved Cells 1410 are used for MBSFNtransmission. MBSFN Area Reserved Cells 1410 are not used for MBSFNtransmission and may be used to perform transmission for otherobjectives. MBSFN Area Reserved Cells 1410 may be allowed for limitedtransmission power, with respect to radio resources allocated to MBSFNtransmission.

FIG. 15 is a diagram illustrating the mapping relation of downlinkchannel used for MBSFN transmission according to an embodiment of thepresent disclosure.

Referring to FIG. 15, MCH 1500 is between MAC layer and Physical layer.MCH 1500 is mapped to PMCH 1505 of Physical layer.

Unicast scheme for transmitting data only to particular UE uses PhysicalDownlink Shared Channel (PDSCH) 1510.

FIG. 16 is a diagram of a structure of downlink frame used in an LTEsystem according to an embodiment of the present disclosure.

Referring to FIG. 16, a radio frame 1600 includes 10 subframes 1605. Thesubframes 1605 are divided into general subframes or ‘subframes forunicast’ 1610 for transmission/receiving data and ‘subframes forbroadcasts’ 1615, which are ‘MBSFN,’ called MBSFN subframe.

There are differences between a general subframe and an MBSFN subframeon the structure and the number, e.g., the number of OrthogonalFrequency Division Multiplexing (OFDM) symbols, the cyclic prefixlength, cell-specific reference signals (CRS), etc.

In Rel-8 and Rel-9 systems, MBSFN subframes are used only for thepurpose of transmitting broadcast data or multicast data. As systemsevolve, since LTE Rel-10, MBSFN subframes may also be used for unicastas well as broadcast or multicast.

In LTE, in order to efficiently use PDSCH, UE devices are separatelyconfigured according to Multi-antenna technology and TM related toReference signal (RS).

Current LTE Rel-10 has TM1˜TM9. Each UE has one TM for PDSCHtransmission. TM 8 is newly defined in Rel-9. TM 9 is also defined inRel-10.

In particular, TM 9 supports SU-MIMO with ranks of maximum 8. TM 9supports transmission of multiple layers. In de-modulation, TM 9 allowsfor transmission of maximum 8 layers by using Rel-10 DemodulationReference Signal (DMRS). The Rel-10 DMRS transmits precoded DMRS;however does not inform the receiving end of a corresponding precoderindex. In order to support TM 9, a format of 2C for Downlink ControlInformation (DCI) is newly defined in Rel-10. UE before Rel-10 does nottry decoding in MBSFN subframes. Therefore, UE before Rel-10 isrequested for upgrade so that they can tray decoding in MBSFN subframes.

In order to transmit/receive unicast data, LTE systems inform PDCCHwhere transmission/reception of real data is performed. PDSCH transmitsreal data. Before the UE receives real data, the UE needs to determinewhether it has information about resources that PDCCH has allocated tothe UE.

On the contrary, MBSFN obtains information about resource assignmentthrough a relatively more complicated process. First of all, eNB informsUE of transmission location of Multicast Control Channel (MCCH)according to MBSFN areas provided by a cell, through broadcastinformation of SIB13. MCCH includes resource assignment information forMBSFN. UE decodes MCCH and detects transmission location of MBSFNsubframes.

As describe above, MBMS provides resource assignment information thoughthe method that differs from unicast according to the related art.Therefore, MBMS can provide information to UE operating in idle mode.MBSM informs UE of MCCH transmission location through broadcastinformation of SIB 13. The entire process of receiving an MBMS serviceas described below referring to FIG. 17.

FIG. 17 is a flow chart that describes a method of receiving MBSFN by UEaccording to an embodiment of the present disclosure.

Referring to FIG. 17, UE 1700 receives SIB1 from eNB 1703 at operation1705. The SIB1 includes scheduling information about other SIBs.

Therefore, UE 1700 needs to have received SIB 1 in order to receiveother SIBs. UE 1700 receives SIB2 from eNB 1703 at operation 1710. MBSFNsubframe configuration list of SIB2, MBSFN-SubframeConfigList IE,indicates subframes available for MBSFN transmission.MBSFN-SubframeConfigList IE includes MBSFN-SubframeConfig IE, indicatingwhich subframe of which radio frames can be MBSFN subframe. Thefollowing table 3 shows the structure of MBSFN-SubframeConfig IE.

TABLE 3 MBSFN-SubframeConfig information element -- ASN1STARTMBSFN-SubframeConfig ::=  SEQUENCE { radioframeAllocationPeriod ENUMERATED {n1, n2, n4, n8, n16,  n32}, radioframeAllocationOffset INTEGER (0..7), subframeAllocation  CHOICE { oneFrame BIT STRING(SIZE(6)), fourFrames  BIT STRING (SIZE(24)) } } -- ASN1STOP

In Table 3, the radio frame allocation period,radioFrameAllocationPeriod, and radio frame allocation offset,radioFrameAllocationOffset, are used to indicate radio frames with MBSFNsubframes. Radio frames satisfying a numerical formula, SFN modradioFrameAllocationPeriod=radioFrameAllocationOffset, have MBSFNsubframes.

System Frame Number (SFN) is used for numbering radio frames from 0 to1023, where the numbering is repeated. The subframe allocation,subframeAllocation, indicates which subframe of radio frames indicatedby the numerical formula is MBSFN subframe. The subframe allocationmakes an indication by unit of one radio frame or unit of four radioframes. When the subframe allocation makes an indication by unit of oneradio frame, it is indicated by oneFrame IE. MBSFN subframes may be inthe 1^(st), 2^(nd), 3^(rd), 6^(th), 7^(th) and 8^(th) subframes of the10 subframes in total in one radio frame. Therefore, the oneFrame IEindicates MBSFN subframe from the listed subframes by using 6 bits. Whenthe subframe allocation makes an indication by unit of four radioframes, it is indicated by fourFrames IE. In order to cover four radioframes, the fourFrames IE indicates MBSFN subframes in the listedsubframes, every radio frame, by using 24 bits in total. Therefore, UEcan correctly detect MBSFN subframes from the subframes by usingMBSFN-SubframeConfigList IE.

If UE 1700 wants to receive MBSFN, it receives SIB13 from the eNB 1703at operation 1715. MBSFN area information list, MBSFN-AreaInfoList IE,of SIB13 includes information about location where MCCH by MBSFN areasprovided by a cell is transmitted. UE receives MCCH using theinformation at operation 1720. The following table 4 showsMBSFN-AreaInfoList IE. Every MBSFN area includes corresponding MCCH.MBDFN-AreaInfoList IE includes MCCH scheduling information of all MBSFNareas. MBSFN-AreaInfo IE includes MCCH scheduling and correspondinginformation. Mbsfn-Areald is MBSFN area Identifier (ID).Non-MBSFNregionLength denotes the number of symbols corresponding to anon-MBSFN area from the symbols in MBFSN subframes. The symbol islocated in the head part of the subframe. notificationIndicator is usedto indicate PDCCH bit informing UE of the change of MCCH information.Mcch-Config IE includes MCCH scheduling information.Mcch-RepetitionPeriod and mcch-Offset are used to indicate a location ofa frame including MCCH. Mcch-ModificationPeriod is a transmission periodof MCCH. sf-AllocInfo indicates a location of a subframe including MCChin a subframe including the MCCH. signallingMCS denotes a subframeindicated by sf-AllocInfo and a Modulation and Coding Scheme (MCS)applied to (P)MCH.

TABLE 4 MBSFN-AreaInfoList information element -- ASN1STARTMBSFN-AreaInfoList-r9 ::= SEQUENCE (SIZE(1..maxMBSFN- MBSFN-AreaInfo-r9Area)) OF MBSFN-AreaInfo-r9 ::= SEQUENCE {  mbsfn-AreaId-r9  INTEGER(0..255),  non-MBSFNregionLength   ENUMERATED {s1, s2}, notificationIndicator-r9  INTEGER (0..7),  mcch-Config-r9  SEQUENCE {  mcch-RepetitionPeriod-r9   ENUMERATED {rf32, rf64, rf128,   rf256},  mcch-Offset-r9   INTEGER (0..10),   mcch-ModificationPeriod-r9  ENUMERATED {rf512 , rf1024},   sf-AllocInfo-r9   BIT STRING (SIZE(6)),  signallingMCS-r9  ENUMERATED {n2, n7, n13, n19}  },  ... }

MBSFN area configuration, MBSFNAreaConfiguration IE, of MCCH indicates alocation of a resource used for MBSFN transmission. UE receives MBSFNsubframes using the location information at operation 1725.commonSF-Alloc is subframes allocated to an MBSFN area.commonSF-AllocPeriod is a period of subframes indicated by thecommonSF-Alloc. Pmch-InfoList IE includes all PMCH configurationinformation about one MBSFN area.

TABLE 5 MBSFNAreaConfiguration message -- ASN1STARTMBSFNAreaConfiguration-r9 ::=  SEQUENCE { commonSF-Alloc-r9CommonSF-AllocPatternList-r9, commonSF-AllocPeriod-r9  ENUMERATED { rf4,rf8, rf16, rf32, rf64, rf128, rf256}, pmch-InfoList-r9 PMCH-InfoList-r9,nonCriticalExtension MBSFNAreaConfiguration-v930-IEs OPTIONAL }MBSFNAreaConfiguration-v930-IEs ::= SEQUENCE { lateNonCriticalExtensionOCTET STRING OPTIONAL, --  Need OP nonCriticalExtension SEQUENCE { }OPTIONAL --  Need OP } CommonSF-AllocPatternList-r9 ::= SEQUENCE (SIZE(1..maxMBSFN-Allocation s)) OF MBSFN-SubframeConfig -- ASN1STOP

UE obtains a location of MBSFN subframe transmitting MTCH of interestfrom MCH scheduling information MAC CE which is one of the MAC ControlElement (CE) of the received MAC PDU at operation 1730. UE decodes theMTCH of interest using MCH scheduling information at operation 1735.

FIG. 18 is a signal flow chart that describes an MBMS counting procedureaccording to an embodiment of the present disclosure.

Referring to FIG. 18, the MBMS counting procedure allows eNB to detectMBMS service of interest or MBMS services that UE operating inconnection mode is receiving. The eNB 1805 transmits a message,MBMScountingRequest, to the UE 1800 at operation 1810. TheMBMScountingRequest message is used to count the number of UE devicesthat are receiving a specific MBMS service that have an interest in theMBMS service. The message includes Temporary Mobile Group Identity(TMGI) IE. TMGI includes Public Land Mobile Network (PLMN) ID andservice ID and is used to indicate a specific MBMS service. The eNB mayinform the UE, by using TMGI, of a detail about what types of MBMSservices it wants to collect. The UE informs the eNB, by usingMBMScountingResponse, of a detail as to whether the UE is receiving orhas an interest in services that the eNB wants to collect at operation1815. The eNB may determine, based on the received collectedinformation, whether it continues broadcasting the current MBMS serviceor broadcasts a new service.

The MBMS counting procedure has a limitation that it can only collectinformation from UE operating in connection mode. In LTE standards, MBMSservices may be received by UE in idle mode as well as in connectionmode. Therefore, in order to measure the correct demand for MBMSservices and to determine real services to be broadcast, MBMS servicesreceived by UE in idle mode need to be collected, in addition to MBMSservices received by UE in connection mode. However, when UE in idlemode reports the information described above to eNB, it needs to trayconnecting to the eNB. The present disclosure provides a method ofeffectively reporting, by UE in idle mode, the information describedabove to eNB.

In embodiment 6 of the present disclosure, when eNB requests a MBMScounting procedure from UE in idle mode by using SIB or MCCH, the UEswitches to connection mode and provides the information described aboveto the eNB. During the process, the UE ignores the current networkcongestion and switches to connection mode. To this end, during the RRCconnection establishment, the UE defines a new cause value indicatingthat connection is made with MBMS counting-related information in theRRC Connection Request message.

FIG. 19 is a signal flow chart that describes a method of reporting MBMScounting information to eNB by UE in idle mode according to a sixthembodiment of the present disclosure.

Referring to FIG. 19, the eNB 1905 detects network congestion atoperation 1910. In order to control network congestion, the eNB maylimit an access attempt by the UE 1900 by using a broadcast controlchannel at operation 1915. When the network is congested as the numberof network users increases, the eNB limits new access attempts by UE inidle mode in order to maintain quality of service. UE that needs toconnect to the eNB determines whether it is allowed for the access byusing specific configuration information provided to the UE. Thespecific configuration information is referred to as ACB. ACB isincluded in SIB2 of SIB that eNB broadcast to provide system informationto UE devices in the cell. The eNB may request a report of MBMS countinginformation from UE devices in idle mode by using SIB or MCCH atoperation 1920. UE devices in idle mode, i.e., not in connection mode,may receive SIB or MCCH broadcast. Therefore, the request may beincluded in an existing SIB or a new SIB. The request may also beincluded in an MCCH, or an MBMS control channel. The information to beincluded in the SIB or MCCH may be configuration information included inMBMS Counting Request message (Alt 1). In that case, UE that hasswitched to connection mode may directly report MBMS countinginformation to eNB without a request message from the eNB. Although thismethod does not need a request message from eNB, it is disadvantageousin that SIB or MCCH has to include a relatively great deal amount ofinformation. As another method, only one indicator for requesting areport may be included in SIB or MCCH (Alt 2). In that case, UE in idlemode receives the indicator and switches to connection mode. After that,UE receives an MBMS Counting Request message from eNB and then reportscounting information about a specific MBMS service indicated by themessage to the eNB. This method is advantageous in that it may use atleast the exiting MBMS counting information and minimize the amount ofinformation to be included in SIB or MCCH. After UE devices in idle modereceive the request and switch to connection mode, they need to reportthe MBMS counting information to the eNB. However, if the UE does notimmediately connect to the eNB because of ACB, it may not report theinformation to the eNB. Since MBMS counting is used to determine whetherthe eNB continues providing the current MBMS service or provides a newservice, etc., it need to be reported to the eNB in time. That is, MBMScounting has a higher order of priority than other Access. However, ifUE devices that need to report the information to eNB cannot beconnected to the eNB due to ACB, the eNB may not obtain informationrequired to manage MBMS services in time. In order to prevent thisproblem, according to the present disclosure, UE devices in idle modethat need to report MBMS counting information ignores the ACB atoperation 1925 and attempts an access. In particular, a new cause valueis defined in an RRC Connection Request message and indicated to eNB atoperation 1930. The RRC Connection Request message is the first RRCmessage that UE transmits to eNB when the UE needs an access to the eNB.The message includes cause values indicating the access objectives of UEto eNB. In LTE standards, the cause values are defined as follows.

-   -   Emergency: Emergency-related access    -   highPriorityAccess: access for specific objective    -   mt-Access: access according to paging    -   mo-Signaling: UE signaling access for signal transmission    -   mo-Data: UE signaling access for data transmission    -   delayTolerantAccess: access with tolerant delay and low order of        priority (primarily applied to MTC devices)

In addition, in the present disclosure, a new cause value,MBMSRelatedAccess, is defined. When the cause value is included in anRRC Connection Request message, the eNB concludes that the UE hasattempted an access to report MBMS counting information. The UE receivesan RRC Connection Setup message from the eNB at operation 1935. The UEreports the MBMS counting information to the eNB by using a specific RRCmessage. An example of the specific RRC message may be RRC ConnectionRequest or RRC Connection Setup Complete. A new RRC message may also bedefined. When UE has already obtained configuration information relatedto the reporting of MBMS counting information through SIB or MCCH, itmay report MBMS counting information to the eNB by using an existing RRCmessage or a new RRC message at operation 1940. On the contrary, when UEhas received an indicator that switches the idle mode to connection modeto report MBMS counting information, through SIB or MCCH, it may reportMBMS counting information to the eNB through an existing MBMS countingprocedure at operations 1940 and 1945.

FIG. 20 is a flow chart that describes operations of UE according to asixth embodiment of the present disclosure.

Referring to FIG. 20, UE in idle mode receives, from eNB, a request toreport MBMS counting-related information to eNB through SIB or MCCH atoperation 2000. The request may also include MBMS counting configurationinformation, according to the alternative. In order to report the MBMScounting information, the UE needs to switch from the idle mode toconnection mode. To this end, the UE triggers access and also ignoresACB if the ACB has been broadcast from the eNB at operation 2005. Thatis, the UE does not determine whether the triggered access is allowed byusing ACB information, but instead ascertains that the access has beenallowed. UE creates an RRC Connection Request message and selectMBMSRelatedAccess with cause IE at operation 2010. The cause valueinforms the eNB that the access is to report MBMS counting information.The UE reports the RRC Connection Request message to the eNB atoperation 2015. The UE waits for an RRC Connection Setup message fromthe eNB at operation 2020. When the UE has successfully received an RRCConnection Setup message in operation 2020, it includes MBMS countinginformation in an RRC Connection Setup Complete and reports it to theeNB at operation 2025. MBMS counting information may be included inother RRC messages. For example, MBMS counting information may beincluded in an RRC Connection Request message or may be defined as a newRRC message.

The procedure was described based on Alternative 1. When the procedureis performed according to Alternative 2, the existing MBMS countingprocedure is used after RRC Connection Establishment.

Embodiment 7

Embodiment 7 provides a method of collecting MBMS counting informationby using a Random Access. The method surveys not an accurate demand fora specific MBMS service by using a specific RRC message, but a demandfor a specific MBMS service by detecting the reception power/energy ofpreamble receiving power or energy for a preamble. Although the methodcannot detect a correct value for a demand for a specific MBMS service,it is advantageous because it can obtain a demand for a specific MBMSservice through a simple procedure. In particular, since embodiment 1needs an RRC connection, the method can reduce load over the entirenetwork when network congestion occurs. Embodiment 2 can detect a demandfor a specific MBMS service without making network congestion worse.

FIG. 21 is a signal flow chart that describes a method of reporting MBMScounting information to eNB by UE in idle mode, according to a seventhembodiment of the present disclosure. FIG. 21 is a signal flow chartthat describes a method of reporting MBMS counting information to eNB byUE in idle mode, according to embodiment 2 of the present disclosure.

Referring to FIG. 21, the eNB 2105 broadcasts configuration informationto collect MBMS counting information to the UE 2100 by using SIB or MCCHat operation 2110. In Embodiment 2, the configuration informationincludes at least one of the following: MBMS service ID, preamble ID,and Random Access CHannel (RACH) resource. Although the configurationinformation may include a plurality of the following: MBMS service ID,preamble ID, and RACH resource, one MBMS service ID needs to correspondto one preamble ID and RACH resource. The preamble is a reservedpreamble used for contention free RACH, in handover, etc. RACH resourcesare radio resources on frequency and time domain. In radio resourceindicated by the RACH resource, UE may transmit a preamble indicated bythe preamble id. If the UE in idle mode is receiving or has an interestin a MBMS service of which ID is identical to the MBMS service IDdescribed above at operation 2115, the UE transmits a preamble indicatedby the preamble ID described above to the eNB by using the RACH resourcedescribed above at operation 2120. The eNB detects receptionpower/energy due to the preamble at the location of the RACH resource atoperation 2125. If the reception power/energy is measured greater than apreset threshold, the eNB ascertains that one or more UE devices in idlemode have an interest in the MBMS service.

FIG. 22 is a flow chart that describes operations of UE according to aseventh embodiment of the present disclosure. FIG. 22 is a flow chartthat describes operations of UE according to embodiment 2.

Referring to FIG. 22, UE in idle mode receives, from eNB, a request toreport MBMS counting-related information to the eNB through SIB or MCCHat operation 2200. The information includes MBMS service id, preambleid, and RACH resource. One MBMS service ID corresponds to one preambleID and RACH resource. The UE stores the configuration information atoperation 2205. The UE determines whether the MBMS service that it isreceiving or has an interest in is consistent with a MBMS serviceindicated by the MBMS service ID at operation 2210. When the UEascertains that the MBMS service that it is receiving or has an interestin is consistent with a MBMS service indicated by the MBMS service ID inoperation 2210, it transmits a preamble, indicated by a preamble IDcorresponding to the MBMS service id, to the eNB by using a radioresource indicated by the corresponding RACH resource at operation 2215.The eNB measures an increase in reception power/energy due to thepreamble in the RACH resource. When the eNB has measured an increase inreception power/energy, it ascertains that there is a demand for thecorresponding MBMS service. The eNB may predict a demand according tothe extent of increase in reception power/energy. Therefore, the eNBuses the prediction information to determine whether it continuesproviding the current MBMS service or provides a new MBMS service.

FIG. 23 is a schematic block diagram of UE in an LTE system according toan embodiment of the present disclosure.

Referring to FIG. 23, the UE device includes MCG-MAC 2310, controlmessage processor 2365, upper layer processors 2370, 2375, and 2385,controller 2380, SCG-MAC 2315, MCG-MAC 2310, transceiver 2305, PDCP2345, 2350, 2355 and 2360, RLC 2320, 2325, 2330, 2335, and 2340.

The transceiver 2305 receives data and control signals through downlinkchannel of a serving cell and transmits data and control signals throughuplink channel. When a plurality of serving cells are configured, thetransceiver 2305 transmits/receives data and control signals to/from theserving cells.

The MCG-MAC 2310 multiplexes data created in the RLCs. The MCG-MAC 2310also de-multiplexes data transferred from the transceiver 2305 andtransfers the de-multiplexed data to corresponding RLCs. The MCG-MAC2310 processes Buffer Status Report (BSR), Power Headroom Report (PHR),etc., triggered with MCG.

The control message processor 2365 is an RRC layer device. The controlmessage processor 2365 processes control messages from the eNB, andperforms corresponding operations. For example, the control messageprocessor 2365 receives an RRC control message and transfersconfiguration information to the controller 2380.

The upper layer processors are configured according to types ofservices. The upper layer processors process data created in userservices, such as FTP, VoIP, etc. and transfer the processed data to thePDCP.

The controller 2380 detects scheduling commands received via thetransceiver 2305, e.g., reverse grants, and controls the transceiver2305 and the Multiplexer-De-Multiplexer to perform the reversetransmission through proper transmission resources in time. As describedabove referring to FIGS. 6 to 22, the controller 2380 controls theoperations of the UE. Although the embodiment of the present disclosureis implemented in such a way that the controller 2380 is separate fromthe PDCP, it may be modified in such a way that part of the functions ofthe controller 2380 may be integrated into the PDCP.

In addition, although the embodiment of the present disclosure isimplemented in such a way that the MCG-MAC 2310, control messageprocessor 2365, upper layer processors 2370, 2375, and 2385, controller2380, SCG-MAC 2315, MCG-MAC 2310, transceiver 2305, PDCP 2345, 2350,2355 and 2360, RLC 2320, 2325, 2330, 2335, and 2340 are separatelyconfigured and they perform functions that differ from each other, itshould be understood that the present disclosure is not limited to theembodiment. For example, it may be modified in such a way that at leasttwo of the following: the MCG-MAC 2310, control message processor 2365,upper layer processors 2370, 2375, and 2385, controller 2380, SCG-MAC2315, MCG-MAC 2310, transceiver 2305, PDCP 2345, 2350, 2355 and 2360,RLC 2320, 2325, 2330, 2335, and 2340 are integrated as one block.

In the following description, the configuration of an eNB in an LTEsystem according to the present disclosure is explained in detailreferring to FIG. 24.

FIG. 24 is a schematic block diagram of eNB in an LTE system accordingto an embodiment of the present disclosure.

Referring to FIG. 24, the eNB includes MAC 2410, control messageprocessor 2465, controller 2480, transceiver 2405, PDCP 2445, 2450, and2455, RLC 2420, 2425, 2430, and scheduler 2490.

The transceiver 2405 transmits data and control signals through forwardcarriers and receives data and control signals through reverse carriers.When a plurality of carriers are configured, the transceiver 2405transmits/receives data and control signals through the carriers.

The MCG 2410 multiplexes data created in the RLCs. The MCG 2410 alsode-multiplexes data transferred from the transceiver 2405 and transfersthe de-multiplexed data to corresponding RLCs or the controller 2480.The control message processor 2465 processes control messages from UEand performs corresponding operations. The control message processor2465 creates control messages to be transmitted to UE and transfers themto the lower layers.

The scheduler 2490 allocates transmission resources to UE at a propertime, considering a buffer status of UE, a channel state, etc., andallows the transceiver 2405 to process signals from the UE or totransmit signals to the UE. The PDCPs are divided into MCG bearer PDCPs2445 and 2450 and a multiple bearer PDCP 2455. The MCG bearer PDCPstransmit/receive data through only MCG. One MCG bearer PDCP is connectedto one RLC. The multiple bearer PDCP transmits/receives data through MCGand SCG. The controller 2480 controls operations of MeNB from among theoperations described above referring to FIGS. 6 to 22.

Although the embodiment of the present disclosure is implemented in sucha way that the MAC 2410, control message processor 2465, controller2480, transceiver 2405, PDCP 2445, 2450, and 2455, RLC 2420, 2425, 2430,and scheduler 2490 are separately configured and they perform functionsthat differ from each other, it should be understood that the presentdisclosure is not limited to the embodiment. For example, it may bemodified in such a way that at least two of the following: the MAC 2410,control message processor 2465, controller 2480, transceiver 2405, PDCP2445, 2450, and 2455, RLC 2420, 2425, 2430, and scheduler 2490 areintegrated as one block.

As described above, according to various embodiments of the presentdisclosure, the apparatus and method can aggregate a plurality ofcarries between eNBs and perform transmission/reception of signals in amobile communication system supporting a plurality of carriers.

In addition, the apparatus and method according to various embodimentsof the present disclosure aggregates a plurality of carriers betweeneNBs and performs transmission/reception of signals in a mobilecommunication system supporting a plurality of carriers, therebyenhancing a signal transmission/reception rate of UE.

While the present disclosure has been shown and described with referenceto various embodiments thereof, it will be understood by those skilledin the art that various changes in form and details may be made thereinwithout departing from the spirit and scope of the present disclosure asdefined by the appended claims and their equivalents.

What is claimed is:
 1. A method for configuring a connection by aterminal, the method comprising: receiving a radio resource control(RRC) message from a base station; determining whether semi-persistentscheduling (SPS) and transmission time interval (TTI) bundling areconfigured based on the RRC message; determining whether dualconnectivity is configured, if the SPS and the TTI bundling areconfigured; determining whether the TTI bundling is configured formaster cell group (MCG) and the SPS is configured for secondary cellgroup (SCG), if the dual connectivity is configured; and configuring anRRC connection based on the RRC message, if the TTI bundling isconfigured for the MCG and the SPS is configured for the SCG.
 2. Themethod of claim 1, wherein the RRC message comprises anRRCConnectionReconfiguration message.
 3. The method of claim 1, furthercomprising: configuring an RRC connection based on the RRC message, ifat least one of SPS or TTI bundling is not configured.
 4. The method ofclaim 1, further comprising: determining whether a number of configureduplink in the MCG is one, if SPS and TTI bundling are configured; andignoring the RRC message and initiating an RRC connectionreestablishment procedure, if the number of configured uplink in the MCGis more than one.
 5. The method of claim 1, further comprising: ignoringthe RRC message and initiating an RRC connection reestablishmentprocedure, if the dual connectivity is not configured.
 6. A terminal forconfiguring a connection, the terminal comprising: a transceiverconfigured to at least one of transmit or receive a signal; and acontroller configured to: receive a radio resource control (RRC) messagefrom a base station, to determine whether semi-persistent scheduling(SPS) and transmission time interval (TTI) bundling are configured basedon the RRC message, determine whether dual connectivity is configured,if the SPS and the TTI bundling are configured, determine whether theTTI bundling is configured for master cell group (MCG) and the SPS isconfigured for secondary cell group (SCG), if the dual connectivity isconfigured, and configure an RRC connection based on the RRC message, ifthe TTI bundling is configured for the MCG and the SPS is configured forthe SCG.
 7. The terminal of claim 6, wherein the RRC message comprisesan RRCConnectionReconfiguration message.
 8. The terminal of claim 6,wherein the controller is further configured to: configure an RRCconnection based on the RRC message, if at least one of SPS or TTIbundling is not configured.
 9. The terminal of claim 6, wherein thecontroller is further configured to: determine whether a number ofconfigured uplink in the MCG is one, if SPS and TTI bundling areconfigured; and ignore the RRC message and initiating an RRC connectionreestablishment procedure, if the number of configured uplink in the MCGis more than one.
 10. The terminal of claim 6, wherein the controller isfurther configured to: ignore the RRC message and initiating an RRCconnection reestablishment procedure, if the dual connectivity is notconfigured.
 11. A method for configuring a connection by a base station,the method comprising: determining to configure transmission timeinterval (TTI) bundling for a terminal on a primary serving cell(PCell); determining whether semi persistent scheduling (SPS) isconfigured for the terminal; determining whether the SPS is configuredon the PCell or a primary secondary serving cell (PSCell), if the SPS isconfigured for the terminal; generating a radio resource control (RRC)message indicating configuration of the TTI bundling on the PCell, ifthe SPS is configured on PSCell; and transmitting the RRC message to theterminal
 12. The method of claim 11, wherein the determining toconfigure TTI bundling for the terminal on PCell is performed based onchannel status of the terminal and based on available transmission powerof the terminal
 13. The method of claim 11, wherein the TTI bundling isnot configured on the PCell, if the SPS is configured on the PCell. 14.A base station for configuring a connection, the base stationcomprising: a transceiver configured to at least one of transmit orreceive a signal; and a controller configured to: determine to configuretransmission time interval (TTI) bundling for a terminal on a primaryserving cell (PCell), determine whether semi persistent scheduling (SPS)is configured for the terminal, determine whether the SPS is configuredon the PCell or a primary secondary serving cell (PSCell), if the SPS isconfigured for the terminal, generate a radio resource control (RRC)message indicating configuration of the TTI bundling on the PCell, ifthe SPS is configured on PSCell, and control to transmit the RRC messageto the terminal
 15. The base station of claim 14, wherein the controlleris configured to determine to configure TTI bundling for the terminal onPCell based on channel status of the terminal and based on availabletransmission power of the terminal.
 16. The base station of claim 14,wherein the TTI bundling is not configured on the PCell, if the SPS isconfigured on the PCell.